/* e_asinf.c -- float version of e_asin.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 */

/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

#include "math.h"
#include "float.h"

static const float one =  1.0000000000e+00;/* 0x3F800000 */
static const float huges =  1.000e+30;
    /* coefficient for R(x^2) */
static const float pS0 =  1.6666586697e-01;
static const float pS1 = -4.2743422091e-02;
static const float pS2 = -8.6563630030e-03;
static const float qS1 = -7.0662963390e-01;

static const double pio2 =  1.570796326794896558e+00;

float
__ieee754_asinf(float x)
{
    double s;
    float t,w,p,q;
    int hx,ix;
    GET_FLOAT_WORD(hx,x);
    ix = hx&0x7fffffff;
    if(ix>=0x3f800000) {        /* |x| >= 1 */
        if(ix==0x3f800000)        /* |x| == 1 */
        return x*pio2;        /* asin(+-1) = +-pi/2 with inexact */
        return (x-x)/(x-x);        /* asin(|x|>1) is NaN */
    } else if (ix<0x3f000000) {    /* |x|<0.5 */
        if(ix<0x39800000) {        /* |x| < 2**-12 */
        if((huges+x)>one) return x;/* return x with inexact if x!=0*/
        }
        t = x*x;
        p = t*(pS0+t*(pS1+t*pS2));
        q = one+t*qS1;
        w = p/q;
        return x+x*w;
    }
    /* 1> |x|>= 0.5 */
    w = one-fabsf(x);
    t = w*(float)0.5;
    p = t*(pS0+t*(pS1+t*pS2));
    q = one+t*qS1;
    s = sqrt(t);
    w = p/q;
    t = pio2-2.0*(s+s*w);
    if(hx>0) return t; else return -t;
}


float asinf(float x)
{
    return __ieee754_asinf(x);
}
